[lmm]

It's physically impossible for a photo to send the same photons into the eye as the original scene did - imagine taking a photo outdoors in sunlight and then viewing that photo indoors, the whitest possible parts of the photo will be literally orders of magnitude darker than the original scene. Similarly you can't reproduce the same colours because you don't have all of the colours available (e.g. there's no way a computer screen using RGB pixels can reproduce the precise wavelength that a sodium lamp gives out). Trying to reproduce the experience of viewing the original scene is the best we can do, and that requires not just physics but biology and psychology. You talk about "eye receptors", but the line where the eye ends and the brain begins is actually very fuzzy - ontogenically your eyes are part of your brain, and the signals passing from eyes to brain are already in a "compressed form" where e.g. a straight line is represented by a single nerve impulse.

[unfocussed_mike]

This explains really well several things I was struggling to explain.

And also introduced me to the word "ontogenically". Thanks twice.